The goals of this project center on the characterization of spatial vision development in macaque monkeys. These monkeys form an animal model that can be used for testing hypotheses about the neural basis for the developmental processes and their disruption in strabismic amblyopia. We will be studying the development of several aspects of spatial vision in normal infant monkeys and in monkeys who have experimentally-induced strabismus in order to evaluate theories of the neural basis of hyperacuity and of the basic spatial deficit in strabismic amblyopia. First, we will address the idea that both normal neonatal foveal processing and strabismic visual processing resemble that in the normal periphery, and investigate the field-based nature of the spatial deficit in experimentally esotropic monkeys. Second, we will attempt to determine the nature of the "sampling" of visual information in normal infant monkeys and investigate the notion that the normal periphery and the strabismic visual system are spatially undersampled. Third, we will undertake physiological and anatomical studies of the neural basis of the effects we have examined psychophysically. The experiments involve two standard methods for behavioral testing: preferential looking and operant conditioning. All psychophysical data will be obtained by one of these methods. Physiological studies, which will be conducted in order to evaluate the neural bases of the psychophysically defined functions, will be accomplished using standard electrophysiological recording techniques. Macaque monkeys are used for these studies so that longitudinal data can be obtained under carefully controlled conditions, and so that the underlying neural function can be studied in animals whose visual function is well-characterized and demonstrated to be similar to that of humans.